Electrolytes for batteries

The early history of ionic liquid research was dominated by their application as electrochemical solvents. One of the first recognized uses of ionic liquids was as a solvent system for the room-temperature electrodeposition of aluminium [1]. In addition, much of the initial development of ionic liquids was focused on their use as electrolytes for battery and capacitor applications. Electrochemical studies in the ionic liquids have until recently been dominated by work in the room-temperature haloaluminate molten salts. This work has been extensively reviewed [2-9]. Development of non-haloaluminate ionic liquids over the past ten years has resulted in an explosion of research in these systems. However, recent reviews have provided only a cursory look at the application of these new ionic liquids as electrochemical solvents [10, 11]. 

Generally, solid electrolytes for battery applications require high ionic conductivities and wide ranges of appropriate thermodynamic stability. 

Until recently, the idea of a recyclable, non-volatile solvent seemed like the stuff of science fiction. But in the 1980s, researchers in the United States were trying to create a new electrolyte for batteries. Instead, they created a colourless, odorless liquid that was composed of nothing but ions—an ionic liquid. 

As a compromise between the above two approaches, the third approach adopts nonactive (inert) materials as working electrodes with neat electrolyte solutions and is the most widely used voltammetry technique for the characterization of electrolytes for batteries, capacitors, and fuel cells. Its advantage is the absence of the reversible redox processes and passivations that occur with active electrode materials, and therefore, a well-defined onset or threshold current can usually be determined. However, there is still a certain arbitrariness involved in this approach in the definition of onset of decomposition, and disparities often occur for a given electrolyte system when reported by different authors Therefore, caution should be taken when electrochemical stability data from different sources are compared. 

Hydrates could play an important role in electrolytes for batteries with active metals. The water, being involved in the hydrate structure, is less active than at the compositions on the water side of the diagram, i.e. between the eutectic and pure water. The rate of the anodic dissolution of the alkali and... 

The first ammonium salt to be recognized as an ionic liquid was obtained in 1914. It was a nitrate with the structure [C2H5NH3]+N03. Many ionic liquids at present being examined were tested in the USA in the 1970s as electrolytes for batteries (the research was financed by the Air Force Office of Scientific Research). It was found that ionic liquids... 

There are several important hydrated forms of alumina corresponding to the stoichiometries A1(0)0H and Al(OH)3. Addition of ammonia to a boiling solution of an aluminum salt produces a form of A1(0)0H known as boehmite, which may be prepared in other ways also. A second form of A1(0)0H occurs in Nature as the mineral diaspore. The true hydroxide Al(OH)3 is obtained as a crystalline white precipitate when carbon dioxide is passed into alkaline aluminate solutions. It occurs in Nature as the mineral gibbsite. Materials sometimes referred to as /1-aluminas have other ions such as Na+ and Mg2+ present. They possess the idealized composition Na2011Al203. They can act as ion exchangers, have high electrical conductivity, and are potential solid state electrolytes for batteries. 

Appreciable ionic conductivity is found in open framework or layered materials containing mobile cations (see Ionic Conductors). Several phosphates have been found to be good ionic conductors and are described above NASICON (Section 5.2.1), a-zirconium phosphates (Section 5.3.1), HUP (Section 5.3.3), and phosphate glasses (Section 5.4). Current interest in lithium ion-conducting electrolytes for battery apphcations has led to many lithium-containing phosphate glasses and crystalline solids such as NASICON type titanium phosphate being studied. ... 

Use (Unstabilized) Production of piezoelectric crystals, high-frequency induction coils, colored ceramic glazes, special glasses, source of zirconium metal, heat-resistant fibers, (hydrous) odor absorbent, to cure dermatitis caused by poison ivy. (Stabilized with CaO refractory furnace linings, crucibles, solid electrolyte for batteries operating at high temperature. 

It should be noted that, in addition to their use as electronic conductors, polymers can also function as ionic conductors. Materials such as poly(ethylene oxide) and certain oligoethyleneoxy-substituted polyphosphazenes and polysiloxanes, which conduct Li" ions, are used in this regard as polymeric electrolytes for battery applications (9]. 

M. Bukowska, P. Szczecinski, W. Wieczorek, L. Nidzicki, B. Scrosati, S. Panero, P. Reale, M. Armand, S. Laruelle, S. Grugeon, Int. Patent Appl. WO 2010023413 Al, 2010. PentacycUc anion salt used as electrolyte for batteries. 

Oleg Borodin works as a scientist at the Electrochemistry Branch of the Army Research Laboratory, Adelphi, MD since 2011. After obtained a Ph.D. degree in Chemical Engineering in 2000 he worked in the area of multiscale modeling of liquid, ionic liquid and polymer electrolytes for battery and double layer capacitor applications, modeling of energetic composite materials, polymers in solutions, and polymer nanocomposites. He coauthored more than a hundred publications and four book chapters. His modeling efforts focus on the scales from electronic to atomistic and mesoscale. 

To achieve high conductance, both reasonable conductivity and mechanical stability in a thin film form are required. Semi-crystalline polymers have superior mechanical characteristics but vastly inferior conductivity properties to those which are fully amorphous (and well above their Tg), since ionic motion does not occur in the crystalline regions. The design of an optimized electrolyte for battery use is in fact more strongly dictated by morphological considerations (which are affected by the choice of dissolved salt) than by the selection of a system containing a solute with a high cationic transference number. 

Electrical and electronic industries Electrodes, sensors, gas separation membrane, fuel cell membrane, solid polymer electrolytes for batteries and supercapacitors... 

It is now well established that solvent-free films can be cast from solutions of polyethers (such as poly(ethylene oxide)) and alkali metal salts, and that these films can display high ionic conductivity. Most of the effort devoted to this field has been based on the potential of such materials as solid-state electrolytes for battery applications. In this context, from viewpoints of both ionic mobility and weight, lithium salts in PEO have attracted the most intensive research and appear to offer the most promise such materials are discussed elsewhere. The preparation of materials displaying both electronic and ionic conductivity raises interesting possibilities both in the field of batteries and sensors and is beginning to attract attention (16). 

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